It is well known to utilize a bailer pump for oil wells. Such systems utilize a reversible electric motor for lowering a bailer on a cable into a well where it is filled, raised, emptied, and recycled. Such systems are useful for recovering oil from shallow low-yield wells.
However, such systems generally use a mechanical type of sensor for determining when the bailer is lowered and contacts the surface of the oil in the well for controlling part of the sequence of operation. Such sensors are subject to wear, and are subject to inadvertent actuation due to the irregularities in the motion of the bailer such as when the bailer moves down the well and encounters the sides of the well.
The present invention is directed to various improvements in an electrical control system for oil well bailer pumps (1) in which the weight of the bailer drives the motor in reverse rotation to generate a voltage for recharging a battery to recover energy to drive the motor to lift the bailer as well as limiting the down speed of the bailer, (2) an electrical sensing circuit monitors the generated voltage and determines the oil level in the well as a drop in voltage corresponds to a decrease in velocity as the bailer hits the surface of the oil, and (3) a dynamic brake reduces the fall velocity of the bailer prior to impacting the oil to decrease the down speed to a safe range.